Electromagnetic kgvice



W. P. CROCKE'TI' ELECTROMAGNETIC DEVICE Filed Dec. 26, 1924 2 Sheets-Sheet 1.

Sept. 4, 1928. 1,683,450

W. P. CROCKETT ELECTROMAGNETIC DEVICE Filed Dec. 26, 1924 2 Sheets-Sheet 2 ilqz.

Patented Sept. 4} 1928.

UNITED STATES WILLIAM I. CROCKETT, OF CHICAGO, ILLINOIS.

. ELECTROMAGNETIC .nnvrcn.

Application filed December 26, 1924. Serial No. 758.021.

invention relates to an improved constructionof electromagnetic devices by which an armature may be given a large amount of rno'v'enr'ient under the action of 'themagnetic tfield producedby an electrom'agnet, the construction being'such that the a1r gap or air .gaps in themagnetic p'ath are mainta ned of small "extent'throughout the entire range of movement of the armtureg More specifically, my invention'conslsts in providing an electromagnet with pole ends of magnetic material which extend laterally from the magnetic core'of the magnet, and then parallel with theaxis of the core to P S ntja l o rcylin w swim, the P allel portions ofthe pole extensions, extending towards e a'ch other; and having disposed outside of them an armature having a similar cylindrical formation on. its inner surface and mounted coaxially with the cylindrical surfaces of the pole ends. so that a small air gap is maintained betweenthe armature and the pole ends, In thisw'vay I arrange the armature for imovenientout'side of the pole extensions insteadoibetiyeen pole extenains k 1S] has beenhcoriiiiioifjpractice in the Pa t, a d" h iw yl'ame l by'p p y 'proportioning the parts, to secure a much greater travel of the armature thanispcssiso b1e' where the armature'is' arranged to move e weeafi pe'lel n b l rbm gnet sumi 'is ha m an igafisia hile t' i' ae is 'ofsufiiciept-lyf I extent; near- 1y pprba T- a t ai .-?i le to 1 simmering th rig p in my fs na ia igass mate a; p dime ic; ifi in .z m "d n i s l ciently and in this 'etl'ectively;prod11 ce a high d gree of ituriiing efl'ort" on the armature.' nreeriyin ut 'my invention I prefer to employ twoielectroinagnets of thef'kind referred'tof construeted and "disposed so that their cylindrical 'pol'ar eirtensions are coaxial abo utf an axis between the. electromagnets. about which az'ris the armature is mounted with. -its cylindrical surface" coaxial therewith: It is n'oti essential'that'the axis of the armature shalllbe in the plane of the axes of m the electromagnets, theparticular location of the armature axis being, determined by the degree of curvature it i's'desired that the cylindrical surfaces of the pole extensions and the armature shall have. The armature is M constructed so that when acted upon by one of the magnets it is movedto a position for the production of a maximum turning effect on it by the action of the second electromagnet when the latter is energized and vice versa. The armature may be employed for awide variety of purposes; for example, it may itself constitute avisnal signalgit may carry a visual signal of any desired kind it may be employed to operate switching devices, and it may, in fact, be employed to actuate any devices requiring a considerable amount; of movement and which itis desired to give alternate positions.

In some cases I find itadvisable to produce a greater amount of turning effort on the armature system than is possible" with on'e'electromagnetactin l as described, and in this event I may employ two pairs of electromagnets, each constructedas referred to and'both pairs arranged to operatethesame moving system of parts, it being understood that in this case two armatures a're p rovidedfwhich are rigidly secured tothe moving.system,'so that by energizing one' magnetofeach pair at the same time the turning'efi'ort of the two electromagnets becomes effective to rotate'or turn the moving'pa rts. :This construction is valuable under some conditions forthe operation of switching mechanism, particularly Where large movement; is desired andconsider'able 'efiort is requiredto move theswiteh blade-s mtoengagement with the conta'cts'and 'disengage'them therefrom. 5

My invention dyvillj'best, be understood 1m reference" to the accompanying drawings shovvin fpreferred n I Figure 1 shows-my device in simple form in front elevation. r Q p Figure 2' a si'de' "elevation of the device shown'in Figure 1. i I

Figure 3 is :i'top vieiv ofithe'clevice shown in Figure- 1 with the armature in aposition corresponding to that shown in'Figuresl and2. j

Figure 4 is a view similar to FigureB show' ing! the armature in its alternate 'position'and with'the top supporting bar removed Figure 5 shows in a view similarto Figure 2 a modified construction in. which the pole ends are provided only with lateral eXten sions having edges concentric with the inner cylindrical surface of the armature and a fl the invinciiln l'ratml in Figure Figure? shows in plan view a modified form of combined magnet end and pole extension.

Figure 8 shows in front elevation "a part of an electromagnet. provided with the magnet end and pole extension construction'shown in Figure 7. J;

Figsure 9 shows in a view similar to Figure 3 a modified construction in which two pairs of electromagnets are employed and switching devices are arranged to be actuated by the armature of the device. Figure 10 is a sectional view of the parts showi in Figure taken along the line 10 10in Figure 11. e

. F igure a front elevation of the parts shown in igure 9.

Figure 12 is a side" elevation of the parts s'hoivni'n Fig irefl, and, Figure 13 is a diagrammatic View illustratiiig in tap 'view a modified construction of my device and wiring connections which th' energiz'in'g', circuit bfeither magnet may openeaamoniaciceu b theoperation of the iii'a'giietenergiaed to operate the armatiii e. p

i Similar niimei'als ,refer V to similar parts throughoiit the several yiews s shoiijii 1-4 inclusive. my device iioii'sists pr ed electromagnets 10 and 11 held in slightlysepa'ra t'ed condition by upper ahdlowei' ietaining bars 12 and 13 of pen-magnate material secured to the cores l 'tand 15 ofsaidniagnets respectively by screws as indicated. the lower screws also serving to secure the magnet assembly to a suitable mounting block 16. -The core 14 has rigidly secured to its .endsabove and be low the windin,' of the magnet, polar extensions ,17 and '18 of magnetic material which, as indicated in Figures 3-a'nd 4', are preferably provided with curved edges concentric about :in axi's preferably in a plane between 'the two eleet'romiignets. At their outer ends, the extensions 17 and 18- have integral portions 19 aud 20 extending front their outer ('UIVQt'l e'dii'es towards each other and sufliciently separated at their adjacentends to insure against the flow of an appreciable amount of magnetic flux between them. The outer surfaces of the extensions 19 and 20 are cylindrical about said axiswhich is preferably parallel with the axes of said electron|agnets. The ends of the core 15 are provided with lateral extensions 21 and 22 simi-v lar to the extensions 17 and l8, and from the extensions 21 and 22, integral extensions 23 and 2-1 extend towards each other in a similar manner to the extensions 19 and 20. The extensions 21, 2 2, 23 and 24 difi'er from the extensions 17, 18, 19 and 20 only in that they are curved in a reverse direction. the outer surfaces of the extensions 23 and 24 being eoaxial with the axis of the outer cylindrical surface; of the extensions 19 and 20. ,1

c eiit the outer surfaces of the extensions 19,-

20, 23 and 24 by integral bent ends 27 and 28 having bearings at their inner ends engaged by bearing screws 29 and located in the mounting bars 12 and 13 respectively, c'oaxially with the common connections of the outer cylindrical surfaces of the extensiohs 19, 20, 23 and 24 and the inner cylindrical surface of the armature 26. The radius of the inner surface of the armature 26 is slightly greater than the radius of the outer surfaces of the extensions 19, 20, 23 and 24, the difference being only enough to provide positive mechanical clearance. between the parts when the armature is turned on its supporting screws 29 and 30. This clearance is purposely iuade 'smallei; than the leii'gtl'r of the air gap 25. It will be also ob seri' ed that the ends 27 and 28 of the armature are adjacent the upper surfaces of the upper polar extensions 17 and 21 and the lower surfaces of the lower polar extension 18 aiid 22 respectively, only sutlicient clearance being provided to insure the parts against mechanical engagement. It will be noted that the bear- 111g screws 29 and- 30 afford a co'nrenien't means for accurately positioning the armature relatively to the upper and lower polar extensions, to maintain the end clearances referred to. V

For the construction illustrated in Figures 14 inclusive. thearmatu'r'e is free to swing until one or the other of its edges engages the corresponding heads of the elect-ro-magnets, as the case may be. Obviously any other desired relation may be secured by differently proportionin'g the armature. and mot-ion of the armature in either direction may be limited in any desired manner.

Vith the construction illustrated in Figures 1-4 inclusive, the annular extent of the armature is such thatwhen it is in either of its extreme positions of movement, complete- 1y enclosing the corresponding cylindrical polar extensions, the outer edge of the armature is substantially in the plane of the edges of the other polar extensions so that the air gap-25 is just enclosed by the armature. Assuming the position of the armature shown in Figure 3, when the electromagnct 10 is energized, the shortest path for the magnetic fiux is from the outer edges of the extensions 19 and 20 to the adjacent edge of the armature "26, the armature itself forming the entire return path for the flu); excepting for the Small amount of. Separation between the ltl'lllfltlll! and the 1?.lt-f'fl3iinil3 11'? 'iii rescribed. Thislcondition, primarily produces a magnetic flux of high density through the edgesofrthe polar extensions referred to and the adjacent edge of the armature. In fact thi'sdensity is so high as to completely saturate the extensions and armature at their edges, and as a result a considerable amount of the magneticflux is required to take a longer path through the air from the extensions 19 andto the edge of the armature, than is represented by the mechanical separation of said extensions from the armature. As-a result, a high degree of turning efi'ort is-exerted on the armature, which at once begins to .move towardsthe position indicated in Figure 4.- The magnetic condition first described is modified somewhat as the armature begins tooverlap the extensions .19

and 20, but-action of th'e'same nature continues for further movement of the armature fort. 'is' still exertedon the: armature by the flux: from" the extensions 17: and 18 through the armature adjacent theairgap 25, so that the; condition of lowest;.reluc tance to magnetic flux-is not' established until the arma ture has 'reached the position indicated in Figure, 4; A similar condition is created when it is desired to'move the armature; from the-positionjindicated iirFigure 4to. the po sition indicatedini'Figureg'ii by energizing. the magnet: 1'1. The ma "netic ac'tiondescribed ii aided by.- maki'ng-t e armature :relatively: t From the i above it will appear; that -I provide means-for po'sitivelymoving an-. armature throughZ-afdistance greatly inexcess of the. air gapandthat thismotionmay be in a first direction -due..to theenergization of one electromagnetj and in an opposite direction due to the energiz'ation of a secondielectromagnets 5 The oscillating movement. of-the armature. referred to, may beemployedto'operate any desired instrumentalities. If desired the oylindrical surface of the armatureitself, or

either of its ends may form a visible indication expressing either one of two conditions as desired, for which the magnets 10. and 11- will be respectively energized.

The construction shown in Figures 5 and 6 is the same as that above described with the exception that the polar extensions 19, 20, 23 and 24 are omitted and the polar extensions 17, 18, 21 and 22 alone are employed, also that in this case the armature 26 has secured thereto in any suitable manner, for example by riveting, a target or signal 31, which may. be given either one'of two positions by move ment of the armature, in substantially the manner above described. In this case, electromagnetic action-takes place between the integral with the parts 2'? and 28 of the armari ture or may be attached thereto in any suitable manner. p

In Figures 7 and 8 I illustrate a simplified detail of construction by which the head of the magnet 33 is of magnetic material formed integrally with the polar extension 34, the extension 34 corresponding to the similar extension 17 used'in the complete structure illustrated in Figures 1-6 inclusive and the extensions being of the kind shown in Figures 5 and 6. inclusive. In this case the head 32 is of course insulated from the winding of the magnet 33 by suitable material as shown at v In the construction shown in Figures 9-12 inclusive, the electromagnetic system consists. of two pairs of magnets 10, 11 and 10, 11, each pair being of a construction similar to that described above in connection with Figures 1 1 inclusive. The two pairs of mag-- nets are secured together by top and bottom plates 12 and 13, respectively, of insulating material which holdthe circular edges of; the polar extensions co axial about the bearings 29,- and -used-..to .support the armature structure. Inthis case, thearmature consists of two parts 26", 26*,eachfor1ned in theananner described in connection with Figs. .1-4;

inclusive, the two .arm atures being joined at. their ends by cross bars 36 and 37 holding the armatures co axially about the-axis ofthe. bearings'29f and 30*.. Thearmature 26-has secured thereto and insulated therefrom, a switch blade 38 which is extended above and below the mounting plates 1-2 and 13? respectively and provided above and below. said, plates with bent ends. 38 and 38 extending substantially parallel with the. mounting plates 12 and 13 respectively. The mounting late 12 carries a switch contact 39 zpreferab y of the jaw. type for engagement by the bent end 38* when the armature system.

is in the position indicated in Figures 91-2 inclusive, and said mounting plate also carries a second switch contact 40 for engagement with the bend 38 when the armature is in its alternate position due to the energization of the magnets 10 and 10". The mounting plate 13 has secured to its lower face a switch contact 41 for engagement by the bent portion 26 [Nil end 38" at the same time the contact 39 is engaged, and a second similar contact 49. for engagement by the bent endBS at the same time that thecontact 40-is engaged. In this way, either the contacts 39 and 41 or the co-n taets 40 and 42 may be Connected by the switch blade 38 depending on the position of the armature system.

The armature 26 has secured thereto and insulated therefrom, a Switchblade-43 similar to the switch blade 38 and having Similar end extensions 43 and 43 for engaging contacts 44 and 45 carried by the mounting plate 12 and similar contacts carried by the mounting plate 13 3 result 'oflwhichthe switch blade 43 connectsithe contact 44 with the similar lower contact at the same time that the contacts 39 and 41 are connected by the switch blade '38, and that the switch blade'43 connects the contact 45* with the'simila'r lower contact at the 'same'tinie that the contacts 40 and 42 are'con-nected by the switch blade 38- Convenient connection may be made with the several switch contacts by the binding screws indicatedi The switeb constrii'cti'o'n described may be used as a double pole-,do'uble throw switch, or for any purpose where it is" desired to alter nately connect two out of four pairs of contacts; Thus' n'iy eleett'omagnetic-system may conveniently be employed to operate switch ing devicesofthetypeiiistdeseribed "or similarfjswitchiifg 'me'chani'sm havingother arrang enients 'o'ffeoiitact'sla' desired-.1

In the c'onstrt'ictionfshown diagrammatically in F i ure an 'el'eetreriia'gnetic system is indicatedsimaar' ttijthatj'shown and described in --comieenonr v'vith" Figures 1 4" in elusive; In this-ease? howeyefithe mounting of ats'ilflicie nb length {to connect the contacts 46 47' -flint-he position of the r rmature- 26' sli'ownin Figuie'B, and'to connect the 'e'on facts 4? and 48 "for the aljternate posit-ion of said armature. i In this view the win'dings'of the elem-ma nets and; 11 areiindicated' diagrammatiballyat :10? and 11,". The 'c-ircuit-connectiqn's'ofthe deyice are as follow'sr'. Mand se m suppiy conductors forreceiiT- ing suitable eleetrie" 'energ"y' from any source (notfsh'ownf, to operatethe magnets 'IOj'and 11. The O'IidubtOi 52 isflcoiinectd with the WhatIclaim'is:

ing 10", the magnet 10 is energized and the ar mature 26 is moved towardsthe magnet 10-. This moves the switch blade 49 from engagement with the contact 46 and into engagement with the contact 48, thus'interrupting the energizing circuit-of the magnet 10 so that current flow isinterrupted by' the operation of the device whether the switch 53 is at once moved to its open position or not- Similarly, if, after the operation described. the switch 54 is closed, the magnet 11 is energized by current flow through its winding 11 and the armature is moved back'to the position indicated in Figiii'c 13. moving the switch blade 49 from engagement. with-the contact 48 and into engagement with the contact-46, thus -in'-' terrupting the energizing circuit of the mag"- net 11 even-though the switch fi4qmayremain in its closed-position until the operation of the device has been completed. The switches '53 and 54 should normally, of course, be in their open position, which be providcd for by any suitable means well known tothe art.

lVhile I have show'n my inventi'on inthe particular embodiments above described, 'it will be understood that I do'not limit myself to these exa etconstruetions', as I may employ eqnii'alents known tothe art at the-time of the filing-of this applicationwithout-depart ing from the scone' ofltheiappended claiinsxfl 1; Inan electromagnetic device, the*coni-' binat-ion ota pair of electromagnets =bars'of non m'azgiietic material securing said'el'ectrm magnets together in substantially parallel relation, 'pol'e pieces having: eurved outer edges and substantiall parallel a'cent edges at each-end of sai electroma inets separa'tie'd a siibst-a-ntialaair ap, polhr 'extem sibns from the *pole piecesio'f ach electromay net extending towards each other and havin cylindrical outen' surtaces'g' the cylindrical ea facesofi said extensions: being "'coaxiulg and an armature pivotally supportexlibyi-said bars for oscillation about common :axis of cylindrical surfacesy'sz'fid armature oon' pris ing a body portion having a cylindrioal annex: surface-separated from said 'cylind rical s-nr faces of said polar extensions by a small'air m gap and laterally- 'extendi ng: I erids=- for "engaging itsfpivotal supports. '1 2. In an electrbmagnetiedevice, the-come binatiorr of a pair of *electromagnts; bars of non-magnetic material; securing -'sEiid':elec 1% tromagnets togetherin substantiallyparallel relation, pole pieces having 'cu'ri'ed enteredges and substantially parallel adjacent edges at each end ofsaid electromagnetsseparated bya substantial air a p'-,-polar-eaten F225 sions from the pole pieces-of eaieh-e'lectro magnet extending towards each 'othe'rand having cylindricalouter surfaces, the-cyliii-- drical surfaces of said extensions being C O--' axial. an arnmturv. pii ntally siipp'rn'tfld b}; rt.

said bars for oscillation about the common axis of said cylindrical surfaces, said armature comprising a body portion having a cylindrical inner surface separated from said cylindrical surfaces of said polar extensions by a small air gap and laterally extending ends for engaging its pivotal supports, and devices for limiting movement of said armature in each direction, the body portion of said armature being so proportioned that for either of its positions of extreme movement the edges of said extensions next to be energized to attract it are substantially in the plane of its adjacent edge.

3. In an electromagnetic device, the combination of a pair of electromagnets, bars of non-magnetic material securing said electromagnets together in substantially parallel relation, pole pieces having curved outer edges and substantially parallel adjacent edges at each end of said elec-tromagnets separated by a substantial air gap, said curved edges being coaxial, and an armature piv otally supported by said bars for oscillation about the common axis of said coaxial edges, said armature comprising a body portion having a cylindrical inner surface separated from said coaxial edges by a small air gap and laterally extending ends for engaging its piv otal supports.

4. In an electromagnetic device, the combination of a pair of electromagnets. bars of non-magnetic material securing said electromagnetstogether in substantially parallel relation, pole pieces having curved outer edges and substantially parallel adjacent edges at each end of said electromagnets separated by a substantial air gap, said curved edges being coaxial, an armature pivotally supported by said bars for oscillation about the common axis of said coaxial edges, said armature comprising a body portion having a c lindrical inner surface separated from sai coaxial edges by a small air gap and laterally extending ends for engaging its pivotal supports, and devices for limiting movement of said armature in each direction, the body portion of saidarmature being so proportioned that for either of its positions of extreme movement the edges of said pole pieces next to be energized to attract it are substantially in the plane of its adjacent edge.

5. In an electromagnetic device, the combination of an electromagnet, pole pieces having curved outer edges, polar extensions from the pole pieces extending towards each other and having cylindrical outer surfaces, said cylindrical extensions being coaxial, and an armature pivotally supported for oscillation about the common axis of said cylindrical surfaces, said armature comprising a body portion having a cylindrical surface separated from said cylindrical surfaces of said polar extensions by a small air gap and laterally extending ends for engaging its pivotal supports.

6. In an electromagnetic device, the com bination of an electromagnet, pole pieces having curved outer edges, said curved edges being coaxial, and an armature pivotally supported for oscillation about the common axis of said coaxial edges, said armature comprising a body portion having a cylindrical inner surface separated from said coaxial edges by a small air gap and laterally extendin ends for engaging the pivotal supports.

x. In an electromagnetic device, the combination of a single coil electromagnet having polar extensions from both its ends provided with curved surfaces, an armature havin g a similarly curved operating surface preseated to said polar curved surfaces and separated therefrom by small air gaps, a pivotal support for said armature mounting it for oscillatory movement maintaining said air gaps substantially constant, and a second similar electromagnet having similar polar extensions similarly related to said armature operating surface for effecting reverse movement of said armature.

8. In an electromagnetic device, the combination of a single coil electromagnet having polar extensions from both its ends pro vided with curved surfaces, an armature having a similarly curved operating surface presented to said polar curved surfaces and separated therefrom by small air gaps, a pivotal support for said armature mounting it for oscillatory movement maintaining said air gaps substantially constant, said curved sur faces being cylindrical and coaxial with said pivotal support, and a second similar electromagnet having similar polar extensions similarly related to said armature operating for effecting reverse movement of said armature.

9. In an electromagnetic device, the combination of an electromagnet, pole pieces having curved outer edges, polar extensions from the pole pieces extending towards each other and having cylindrical outer surfaces, said cylindrical extensions being coaxial, and an armature pivotally supported for oscillation about the common axis of said cylindrical surfaces, said armature comprising a body portion having a cylindrical inner surface separated from said cylindrical surfaces of said polar extensions by a small air gap and laterally extending ends for engaging its pivotal supports, the body portion of said armature bein relatively thin magnetic material decreasing the total reluctance of the magnetic path for movement of said armature.

In witness whereof, I hereunto subscribe my name this 24th day of December, A. D. 1924.

WILLIAM P. CROOKETT. 

